Various mobile devices have keys for receiving user input such as text, numbers or user commands. Such keys often contain a legend printed on a key cap, as in a wired or wireless telephone or Personal Digital Assistant (PDA) device. On some occasions, the function of a key may vary and a legend associated with the key is displayed. For instance, Nokia™ 6110 mobile telephone had a display and two so-called soft-keys which were keys in the proximity of the display and whose legends were shown on the display during normal operation of the mobile telephone.
The keys of the aforementioned mobile telephone were implemented by means of a key mat providing user actuatable keys as protrusions which would relay the user actuation onto co-aligned membrane switches deposited onto a surface of a circuit board inside the mobile telephone. The keys were supported sideways in respect to the direction of their actuation by a key frame or so-called A-cover that contained co-aligned apertures for the keys. Consequently, a key arrangement was provided which occupied a relatively small depth and provided keys reasonably robust and convenient to use. The key arrangement is also very well suited for mass production, as it provides a joint assembly process for numerous keys and is thus relatively fail-safe as well. However, such keys must generally be supported over their entire surface such that they cannot be placed quite next to the display, for instance to provide a pair of a key and its associated legend in so-called soft key concept.